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🍬 Sugarcane Breeding Basics

Botanical traits, crossing behavior, and breeding relevance of sugarcane.

This lesson covers core principles and exam-focused points from this topic in plant breeding.

Sugarcane ( _ Saccharum officinarum _ ) (2n = 80)

Cross pollination is the rule in sugarcane. Self male and female sterility, protogyny and

hanging down of anthers away from the stigma at the time of anthesis promote self pollination.

Usually anthesis will be in early morning between 5 am and 6 am. Maximum anthesis between 6

am and 8 am. Stigma protrudes out first and anthers dehisce afterwards. Flower opening will be

from top to downwards. It will take about 10 days for complete opening of spikelets. Flowering

in sugarcane is location specific and influenced by environment. Natural pollination is by wind

( Anemophily )

Selfing

Selfing is done by covering the arrow with a bamboo frame work or cage which is

covered with muslin cloth or polythene paper. Such a cover is commonly called lantern. It

prevents accidental cross pollination. The lantern has to be supported by bamboo poles. The

lantern has to be opened once in a day to reduce the temperature that my build up inside during

the day time. This is done preferably during the afternoon hours between 12am and 4pm. Usually

the cover has to be retained in position till the seeds are set. Within one week or 10 days we can

get selfed seeds. This selfing method is followed in Sugarcane Breeding Institute, Coimbatore.

Crossing

Hybridization is very difficult.

  1. It is mostly vegetatively propagated. Some varieties seldom flowers outside tropics.

Some varieties flowers once in 6 to 8 months. It is highly controlled by photoperiods.

  1. Spikelets are minutes. So, hand emasculation is not possible.

  2. Self sterility of both pollen and ovule predominates in almost in all the varieties.

  3. Hot water treatment can not possible.

Hybridization methods

Coimbatore method

During flowering period, the sugarcane stem will be cut leaving one or two bud. The cut

stem can be transferred to a mud pot having moist mud. Within 10 days the buds will develop

into roots and there will be good root system. This can be transferred to the breeding block. In

the crossing block, the male and female plants are covered with common lantern . Free shedding

pollen over female plant will occur. We can harvest both selfed and crossed seeds from the

female parent. The selfed seeds can be identified by chromosome number by raising it in the

nursery. Selfed seeds thus removed retaining crossed seeds.

Marcotting method

During flowering, cut around the stem and tie a polythene bag with nutrients (growth

medium). The bud near cut end give rise to roots. This can be cut and used for hybridization

purposes. This method is called marcotting. Practiced in Sugarcane Breeding Institute,

Coimbatore.

Lantern method

Providing Lantern for a female plant before anthesis starts. From the desired male parent

cut the arrow. That arrow can be introduced into the Lantern and shaken up and thereby crossing

can be effected. This will be repeated for 2-3 days in order to have more seed set.

Hawaii method (Sulfurous acid Technique)

A sulfurous acid solution keeps the inflorescence alive for several weeks. Here, we cut

both mal and female flowering arrows along with small portion of stem. These cut end will be

immersed in a vessel containing 0.01% sulphuric acid and 0.01% phosphoric acid. The cut end

at the lab is brought nearer and effect cross pollination. They absorb the weak acids. We have to

add weak solution daily to replace the acid taken by stem. Once in a week we have to

completely change the solution. This is done for 20-30 days. During this time, the seed will

mature.

In modified method of this, the female plant alone is cut and kept in weak acid at the time of

flowering the male parent can be brought nearer and the pollen can be shed by shaking as done in

Lantern method.

Emasculation and Pollination Techniques in Cotton

Selfing

In the selfing of cross-pollinated species, it is essential that the flower are bagged or

otherwise protected to prevent natural cross-pollination. Selfing and crossing are essential in

crop breeding. It is important that the breeder, master these techniques in order to manipulate the

pollination according to his needs. The exact procedure that he

crop.

In the case of wheat, rice, barely, groundnut etc., the plant is permitted to have self

pollination and the seeds are harvested. It is necessary to know the mode of pollination. If the

extent of natural cross pollination is more, then the flowers should be protected by bagging. This

will prevent the foreign pollen to reach the stigma. Seed set is frequently reduced in ear heads

enclosed in bags because of excessive temperature and humidity inside the bags. In crops like

cotton which have larger flowers the petals may fold down the sexual organs and fasten, there by

pollen and pollen carrying insects may be excluded.

In certain legumes which are almost insect pollinated, the plants may be caged to prevent

the insect pollination. In maize, a paper bag is placed over the tassel to collect pollen and the

cob is bagged to protect from foreign pollen. The pollen collected from the tassel is transferred

to the cob.

Emasculation

Removal of stamens or anthers or killing the pollen of a flower without the female

reproductive organ is known as emasculation. In bisexual flowers, emasculation is essential to

prevent of self-pollination. In monoecious plants, male flowers are removed. (castor, coconut) or

male inflorescence is removed (maize). In species with large flowers e.g. (cotton, pulses) hand

emasculation is accurate and it is adequate.

Methods of Emasculation

Hand Emasculation

In species with large flowers, removal of anthers is possible with the help of forceps. It is

done before anther dehiscence. It is generally done between 4 and 6 PM one day before anthers

dehisce. It is always desirable to remove other young flowers located close to the emasculated

flower to avoid confusion. The corolla of the selected flower is opened with the help of forceps

and the anthers are carefully removed with the help of forceps. Sometimes corolla may be

totally removed along with epipetalous stamens e.g. gingelly.

In cereals, one third of the empty glumes will be clipped off with scissors to expose

anthers. In wheat and oats, the florets are retained after removing the anthers without damaging

the spikelets. In all cases, gynoecium should not be injured. An efficient emasculation

technique should prevent self pollination and produce high percentage of seed set on cross

pollination.

Suction Method

It is useful in species with small flowers. Emasculation is done in the morning

immediately after the flowers open. A thin rubber or a glass tube attached to a suction hose is

used to suck the anthers from the flowers. The amount of suction used is very important which

should be sufficient to suck the pollen and anthers but not gynoecium. In this method

considerable self-pollination, upto 10% is like to occur. Washing the stigma with a jet of water

may help in reducing self-pollination; however self pollination can not be eliminated in this

method.

Hot Water Treatment

Pollen grains are more sensitive than female reproductive organs to both genetic and

environmental factors. In case of hot water emasculation, the temperature of water and duration

of treatment vary from crop to crop. It is determined for every species. For sorghum 42-48˚C

for 10 minutes is found to be suitable. In the case of rice, 10 minutes treatments with 40-44˚C is

adequate. Treatment is given before the anthers dehiscence and prior to the opening of the

flower. Hot water is generally carried in thermos flask and whole inflorescence is immersed in

hot water.

Alcohol Treatment

It is not commonly used. The method consists of immersing the inflorescence in alcohol

of suitable concentration for a brief period followed by rinsing with water. In Lucerne the

inflorescence immersed in 57% alcohol for10 second was highly effective. It is better method of

emasculation than suction method.

Cold Treatment

Cold treatment like hot water treatment kills the pollen grains without damaging

gynoecium. In the case of rice, treatment with cold water 0.6OC kills the pollen grains without

affecting the gynoecium. This is less effective than hot water treatment.

Genetic Emasculation

Genetic/ cytoplasmic male sterility may be used to eliminate the process of

emasculation. This is useful in the commercial production of hybrids in maize, sorghum

pearlmillet, onion, cotton and rice etc.,

In many species of self-incompatible cases, also emasculation is not necessary, because

self-fertilization will not take place. Protogyny will also facilitate crossing without emasculation

(e.g.) Cumbu.

Use of Gametocide

Also known as chemical hybridizing agents (CHA) chemicals which selectively kills the

Maleic hydrazide for cotton and wheat.

Bagging

to prevent random cross-pollination.

Pollination

The pollen grains collected from a desired male

parent should be transferred to the emasculated flower.

This is normally done in the morning hours during

anthesis. The flowers are bagged immediately after

artificial crossing.

Tagging

The flowers are tagged just after bagging. They are attached to the inflorescence or to the flower

with the help of a thread. The following may be recorded on the tag with pencil.

  1. Date of emasculation

  2. Date of pollination

  3. Parentage

  4. No. of flowers emasculate

Summary Cheat Sheet

Quick Recall Points

  • This lesson focuses on key plant breeding concepts, terminology, and exam-relevant applications.
  • Review major definitions, classifications, and method-wise distinctions from the sections above.
  • Revise tables and examples from this lesson for fast pre-exam recall.

Exam Traps

  • Do not confuse similarly named breeding methods without checking their core selection logic.
  • Pay attention to crop-specific examples because the same principle can behave differently by species.

References

1 source • [1]

[1]

Standard Plant Breeding Class Notes (GPBR211)

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